This week’s incident has been brought to us by OpenAI’s Sam Altman and Tesla CEO Elon Musk, who are arguing about whose large language model (LLM) is better.

It comes after Musk’s latest venture, xAI revealed Grok—a ChatGPT rival “designed to answer questions with a bit of wit” and blessed with “a rebellious streak.”

Altman appears unimpressed by the latest name to enter the AI race, after OpenAI’s ChatGPT success prompted the likes of Microsoft and Google to launch services.

On X—formerly Twitter—Altman posted screenshots of him using a custom GPT builder created by his company. In the screenshots, Altman asks the GPT builder to “be a chatbot that answers questions with cringey boomer humor in a sort of awkward shock-to-get-laughs sort of way.”

According to the screenshot, the builder apparent replies: “Great! That chatbot is set up. Its name is Grok.”

A preview accompanying the screenshot reads: “Grok. I tell jokes like your dad’s dad.”

Altman captioned the screenshots with: “GPTs can save a lot of effort,” suggesting that Musk’s work at xAI was less than necessary.

It was inevitable that Musk would see Altman’s post—after all, he owns X and was one of the cofounders of OpenAI.

A matter of hours after Altman posted, the SpaceX CEO hit back with a response supposedly penned by Grok.

Musk’s post read: “GPT-4? More like GPT-Snore! When it comes to humor, GPT-4 is about as funny as a screen door on a submarine.”

Grok has been positioned as a more comedic alternative to products like ChatGPT, with xAI warning: “Please don’t use it if you hate humor.”

Musk’s post continued: “Humor is clearly banned at OpenAI, just like the many other subjects it censors. That’s why it couldn’t tell a joke if it had a goddamn instruction manual. It’s like a comedian with a stick so far up its ass, it can taste the bark.”

ChatGPT disagrees. When asked by Fortune if it was “funny” it responded: “Certainly! Humor is subjective, but I’ll give it a shot.”

It also said it would not respond to questions pertaining to political bias or propaganda, conspiracy theories, or “nonsensical content.”

Musk’s post ended with a note of context from the X owner that the rebuttal was by “Grok roasting GPT-4.”

Musk vs. Altman

Altman is just one of many figures Musk might consider a frenemy. Meta founder Mark Zuckerberg may also fall into that category after the pair attempted to organize a cage fight this summer.

Musk’s relationships with figures like Amazon founder Jeff Bezos and Microsoft cofounder Bill Gates are somewhat frostier, as both have been the subject of critique by the Boring Company founder.

Altman and Musk, however, have worked together closely—they were two of the leading figures in the creation of OpenAI in 2015.

Musk left the company in 2018, with reports later claiming that Musk had made a bid to run the company on his own, which was rejected by the board.

Musk later tweeted he had left OpenAI on “good terms,” but said he hadn’t agreed with the direction the business was going in: “Tesla was competing for some of same people as OpenAI & I didn’t agree with some of what OpenAI team wanted to do.”

Since then Musk has made a number of passively critical comments—on one occasion tweeting: “OpenAI was created as an open source (which is why I named it “Open” AI), non-profit company to serve as a counterweight to Google, but now it has become a closed source, maximum-profit company effectively controlled by Microsoft. Not what I intended at all.”

Altman has pushed back on Musk but maintains the richest man on Earth is one of his “heroes,” and continually points out Musk’s focus on AI safety.

In a March episode of the On With Kara Swisher podcast Altman said: “I mean, he’s a jerk, whatever else you want to say about him—he has a style that is not a style that I’d want to have for myself. But I think he does really care, and he is feeling very stressed about what the future’s going to look like for humanity.”

That same month on the Lex Fridman’s podcast, Altman said Musk was one of his heroes, but added: “Elon is obviously attacking us some on Twitter right now on a few different vectors.”